Process for producing ceramic precursor powders without gel formation

Abstract

The addition of an aqueous solution containing one or more cations intended in a metal oxide ceramic product to a base to precipitate a calcinable metal oxide ceramic precursor reduces gelation problems during the precipitation of the precursor.

We claim: 
     
       1. In a process for forming a ceramic precursor composition, suitable for calcining to form a metal oxide ceramic product, by the combining of an aqueous solution containing at least one metal cation for the ceramic with a concentration of from about 15 gm to 40 gm of metal cation, expressed as oxide, per 100 ml of water, and base precipitating agent to form a precipitate of the ceramic precursor composition, wherein the improvement comprises adding the aqueous solution to the base precipitating agent to produce a pH above the zero point charge for the precipitate and to reduce gelation during the formation of the precipitate which comprises agglomerated particles of 25 to 100 micron size. 
     
     
       2. A process as claimed in claim 1 wherein the base is ammonium hydroxide. 
     
     
       3. A process as claimed in claim 1 wherein the cation is zirconium. 
     
     
       4. A process as claimed in claim 1 wherein the cation is a mixture of zirconium and yttrium. 
     
     
       5. A process as claimed in claim 2 wherein the cation is zirconium. 
     
     
       6. A process as claimed in claim 2 wherein the cation is a mixture of zirconium and yttrium. 
     
     
       7. A process as claimed in claim 4 wherein the pH during precipitation is kept above about 9. 
     
     
       8. A process as claimed in claim 6 wherein the pH during precipitation is kept above about 9.